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John Rumm John Rumm is offline
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Default Roof truss change.

On 08/06/2021 14:36, Chris Bacon wrote:
On 08/06/2021 11:47, John Rumm wrote:
On 07/06/2021 18:37, Chris Bacon wrote:

For 5m span, front of concrete prefab. It was a simple king post
truss design, with the bottom of the king post also bolted via a
bracket to a vertical post netween the two sets of opening doors (1
pair each side) where the word "then" in the pic. is.

The new truss reduces the height of the apex, as well as raising the
eaves height for headroom inside. It will probably also be fixed to a
vertical central post under to floor.
Rough sketch at:

Any ideas for new bracing? It's in 30mm by 30mm by 3mm equal angle.

There is a prefab "low profile" truss design that adds extra height at
the eves and uses a shallower pitch to give less ridge height. That
does use a number of extra bracing members to achieve the stiffness.
There is a picture of one he

(1st graphic, second row, 5 down)

That looks very Howe-like. I now have a modified king-post/Howe design,
which I have tested empirically by dangling off it. I'll see if I can
post a picture somewhere.

You can post pictures on the wiki if you want... (drop me an email if
you need an account created)

An extra row of block on top of the wall might be another option...

Prefab concrete (sectional). Planning, costs are relevant.

If you are making it higher at the eves, I doubt it matters much how you
do it from a planning PoV. (and blocks are probably cheaper than timber
- although I understand the current wall thickness might be rather limited).



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